I have to solve this problem on MATLAB and I'm not sure how.

What are the (a) magnitude and (b) direction of the net electrostatic force on particle 4 due to the other three particles? All four particles are fixed in the xy plane, and q1 = 3.20 1019 C, q2 = +3.20 1019 C, q3 = +6.40 1019 C, q4 = +3.20 1019 C, 1 = 35.0, d1 = 3.00 cm, and d2 = d3 = 2.00 cm.

k=8.99E9; %Constant

% charge experiencing the force

q(1,1)=4E-6;

x(1,1)=0;

y(1,1)=0;

% surrounding charges

q(2,1)=-6.0E-6;

r(2,1)=0.15;

x(2,1)= r(2,1).*cosd(73);

y(2,1)= r(2,1).*sind(73);

q(3,1)=-5.0E-6;

r(3,1)=0.1;

x(3,1)=r(3,1).*cosd(0);

y(3,1)=r(3,1).*cosd(0);

for i=2:3;

% displacement between charges

A=x(i,1)-x(1,1); % x displacement

O=y(i,1)-y(1,1); % y displacement

angle=atan(O/A); % angle with respect to +x axis *

% if statement below corrects angle for indiscernible quadrants

if (O/A)>0 & A<0;

angle=angle+pi();

elseif (O/A)<0 & A<0;

angle=angle+pi();

end

% calculates Coulomb's force

F1i(i-1,1)=k*abs(q(1,1))*abs(q(i,1))/(r(i,1).^2);

F1iX(i-1,1)=F1i(i-1,1)*cos(angle);

F1iY(i-1,1)=F1i(i-1,1)*sin(angle);

% if statement corrects for repulsive forces

if q(1,1)*q(i,1)>0;

F1iX(i-1,1)=-1*F1iX(i-1,1);

F1iY(i-1,1)=-1*F1iY(i-1,1);

end

end

%Results

FX=sum(F1iX) %sum of x components

FY=sum(F1iY) %sum of y components

F=sqrt(FX^2+FY^2) %magnitude of vector sum

Th=atand(FY/FX); %angle in degrees from positive x axis*

if (FY/FX)>0 & FX<0; %corrects for quadrant issue

Th=Th+180;

elseif (FY/FX)<0 & FX<0;

Th=Th+180;

end

Th %corrected angle in degrees